The above-identified prior art discloses novel intermodal vehicles for use in forming a train of highway trailers including leading and trailing trailers which are interconnected to each other and supported by the intermodal vehicles. The design of the intermodal vehicle of this invention, as well as the prior art referred to above, is intended for use with highway trailers of all configurations, including trailers especially designed to haul so-called "ISO" shipping containers. Each of the highway trailers includes leading and trailing coupler socket assemblies at each end, each of the socket assemblies being apertured for receiving a coupling pin. The intermodal vehicle is characterized by two rail wheel assemblies, lower frame means in which the rail wheel assemblies are supported, and upper lifting frame means supported on the lower frame means by spring means. The spring means are air springs which are so arranged that when air is removed from the air springs, the upper lifting frame means will descend toward the lower frame means, and when air is introduced into the air springs, the upper lifting frame means will rise, at the same time raising any highway trailers which may be resting upon the load carrying surfaces. The upper lifting frame means includes leading and trailing upwardly presented load carrying structures, each of the load carrying structures having an upper trailer support surface for engaging the bottom of the trailers. In addition, each of the load carrying structures also carries a coupler tongue which is adapted to be received in the coupler socket assemblies, each tongue being provided with an aperture. A vertically oriented coupling pin is carried by each of the load carrying structures, which coupling pin is vertically moveable from a position below the trailer support surface to a position where it passes through the apertured socket assemblies for securing a tongue within the apertured socket assembly. WO 94/21503 discloses that the upper frame means may be in two sections, each independently moveable, whereas the above-identified U.S. patent discloses only a single upper frame. Whether or not a split upper frame is used, it is still essential that each tongue be supported for limited pivotal, rolling and pitching movement. It is also a feature of the above-referenced designs that the lower frame means are steerable with respect to the upper frame means. In the above-referenced designs, the load carrying structures are shiftable transversely, that is to say, from side to side perpendicular to the longitudinal centerline of the intermodal vehicle to facilitate the alignment of the trailer as it is connected to the intermodal vehicle. Additional features are disclosed in the foregoing patent and published application.